Sensory signals play an important role in communicating key benefits to the consumer. For example, when using toothpaste there is typically no immediate signal that the product has worked as promised or done anything during use. A visual cue, such as the foam changing color from white to blue could dramatically improve this perception but the art reports that such technologies may not be currently feasible.
Moreover, a need exists to control the rate at which this color change occurs so that the signal could be used to ensure consumer compliance (e.g., to ensure a child has brushed adequately).